Help Electrics Question

[phil r]

Hi I am planning to wire in a cooling fan override switch into my 98 Elise as I don’t trust the otter switch (thermostat switch) as the engine temp went up to 104 degrees in traffic this morning. Having prised out the blank switch on the right of the dash (next to the hazards switch) I have found a socket wired for lighting-power and ignition power and a white with blue striped wire attached to the switched ignition connector on the extra switch I have bought (another fog light switch which I plan to change the little white logo form a fog symbol to a little fan symbol). Where does this little White with blue striped wire go? Is it connected to anything? I want to connect it to the radiator fan relay in parallel with the otter switch wire but I can’t find out where it comes out. Any ideas. Oh do you need to get under the car to unbolt the fuse box? (I want to fuse the connection)

Thanks loads
Phil

[phil r]

Hmm Just checked the elise faq site, the cooling is controlled by the ECU, I will have to change the witing so that I dont fry the ECU, looks like a second relay controlled by the new switch will be needed in parallel with the first fan relay.

Tho' if the ECU controls the fan why did it not come on and what temperature should you panic at?
Cheers
Phil

[DanH]

Or get a remote thermostat so that its measuring temp at a better place. Check out Eliseparts for info.

Also if it comes on at 104 on an S1 I think your stat is nackered anyway. The S2 comes in at 105, but the S1 I thought was a fair bit lower.

[fergusd]

The fan activation temp is in no way related to the thermostat function, or whether you fit a remote stat.

The ECU has a seperate temp sensor on the coolant outflow elbow on the gearbox end of the engine. It's the blue one.

www.elise-faq.info/content/cooling/index.php#CoolantTemperatureSensors

Your problem very likely lies in one of two areas.

1. Cooling fan/relay fault, you need to test the relay and fan to make sure there's absolutely nothing wrong with it.

2. ECU temp sensor problem, this could either be a faulty sensor (not unusual) or a bad connection to it (not ususual)

Personally I'd suspect 2 but I'd test 1 just to be sure.

If you still insist on fitting a switch then you can simply ground the ECU end of the fan relay (one end of the coil is is to supply, the other end is earthed by the ECU when it wants to run the fan, it shouldbe safe to ground it with a switch also).

You additional relay idea is also fine . . .

If you don't already have the schematics then I'd download some from the internet.

Edited to say :

Because the instrument temp display is read using a seperate temp sensor it is entirely possible and very common that the fan activation temp on one car to the next is slightly different.

In general real temp switching is ECU sensor 100 on and ECU sensor 90 off, this may not read 100 and 90 on the stack.

The thing to look for is - has the fan activation temp changed from what it used to be ?.

In any case 104C is perfectly acceptable, the cooling system is pressurised to withstand 120C, although you should never ever get to that in the UK.

On at 104C off at 94C could well just be sender tolerances, in my experience these things drift with time.

Fd

>> Edited by fergusd on Wednesday 5th February 22:21

[spunagain]

(Philr in works disguise!) The temperture sender may well be it. I have also noticed some pinking if I dont use super unleaded, I thought this was prabably due to a timing change (seemed to happen after the cam belt change) but could it be temperate related?
Thank for all your advice, where can I download the schematics?
Cheers
Phil

[loserkid]

Should you need to put Super Unleaded in? K Series SHOULD be fine on normal 95ron stuff.

[fergusd]

I guess there will be some timing map changes due to temp, there will definately be fuel map changes, so it'll run rich or lean depending on the failure mode.

However

I don't think so.

I'd check the plugs/ht leads as they seem to fail and cause pinking in the elise quite often, not sure why . . .

Fd

[fergusd]

Schematics . . .

Kazaa, or have a scan on the british cars bbs, someone usually has them online

If you're stuck, mail me offline and we;ll see what can be done . . . not that I would know where to obtain such illegally copied material, as that would be illegal, and only bad people break the law . . .

fd